The Viral Vector Core Lab will assist the affiliated projects with large scale preparation and purification of viral vectors for the program project. This entails maintaining stocks of all necessary shuttle vectors and cell lines, performing the extensive serial passaging needed for amplification of viral stocks, and purifying these viral stocks by CsCl density gradient centrifugation. Finally, the core lab will assay the purified products to determine the titers of "gutted" vector and helper virus,a s well as to detect any possible contamination with replication competent adenovirus.